According to the U.S. Energy Information Administration (EIA), crude oil production from unconventional reservoirs accounted for almost 50% of total U.S. crude oil production in 2017. Unconventional reservoirs include reservoirs such as tight sands, gas and oil shales, coalbed methane, heavy oil and tar sands. These reservoirs typically have extremely low permeability (nano-darcy to micro-darcy), and require special recovery operations (such as horizontal drilling and hydraulic fracturing) in order to produce the oil. During a typical hydraulic fracturing treatment, for example, fracturing fluid (primarily water with proppants, such as sands, suspended in it) is pumped downhole into the formation at high pressure to create cracks in the unconventional reservoir. The proppants remain in the fractures after the treatment is completed, and hold the fractures open. The reservoir conductivity is therefore enhanced by the hydraulic fracturing treatment, allowing hydrocarbon flow to the wellbore.
Despite of the effectiveness of hydraulic fracturing and similar treatments in promoting hydrocarbon flow, the industry lacks tools to monitor unconventional reservoir performance after the treatment. Traditional methods such as microseismic imaging and borehole gauges rely on indirect measurements of physics-based parameters (including, but not limited to, acoustic, pressure, and the like) to infer the reservoir performance. Those methods are typically very expensive (i.e., costing multi-millions of dollars), and the results can be unreliable depending on the interpretation methods used.
Examples of prior art methods and system are described in the following references, all of which are incorporated herein by specific reference in their entireties for all purposes:
U.S. Pat. No. 9,074,465 B2, filed Dec. 9, 2009, entitled “Methods for Allocating Commingled Oil Production.”
U.S. Pub. No. 2011/0297370, filed May 18, 2011, entitled “Hydrocarbon Production Allocation Methods and Systems.”
U.S. Pub. No. 2013/0138360 A1, filed Nov. 30, 2011, entitled “Allocating Oil Production from Geochemical Fingerprints.”
U.S. Pub. No. 2014/0250999 A1, filed Mar. 28, 2012, entitled “Method and System for Reservoir Surveillance Utilizing a Clumped Isotope and/or Noble Gas Data.”
U.S. Pat. No. 9,638,821 B2, filed Mar. 16, 2015, entitled “Mapping and Monitoring of Hydraulic Fractures using Vector Magnetometers.”
U.S. Pub. No. 2017/0260854 A1, filed Sep. 14, 2017, entitled “Hydraulic Fracture Monitoring by Low-frequency DAS.”
U.S. Pub. No. 2018/0016890 A1, filed Sep. 25, 2017, entitled “Hydraulic Fracture Analysis.”
U.S. Pub No. 2018/0313807 A1, filed Apr. 26, 2018, entitled “Time-series Geochemistry in Unconventional Plays”
Bennett, B. et al., 2009, Oil Fingerprinting for Production Allocation: Exploring the Natural Variations in Fluid Properties Encountered in Heavy Oil and Oil Sand Reservoirs, 2009 CSPG CSEF CWLS Convention, Calgary, Alberta, Canada.
Elsinger. R. J., et al., 2010, Otter-Eider Geochemical Production Allocation: 6+ Years of Continuous Monitoring to Provide Fiscal Measurements for Hydrocarbon Accounting, AAPG Hedberg Conference, Vail, Colo., Jun. 8-11, 2010.
Rasdi, F. et al. 2012, An Investigation of Vertical and Lateral Communication in an Unconventional Oil Reservoir Using Geochemistry and Reservoir Simulation, SPE Canadian Unconventional Resources Conference, Oct. 30-Nov. 1 2012, Calgary, Alberta, Canada.
Nouvelle, X., et al., 2012, Novel Method of Production Back-Allocation Using Geochemical Fingerprinting, the Abu Dhabi International Petroleum Exhibition & Conference, Abu Dhabi, UAE, Nov. 11-14, 2012.
Lareau, H. et al., 2016, Utilizing Geochemical Analysis in Unconventional Reservoirs to Allocate Produced Oils to Stratigraphic Zone, AAPG/SEG International Conference and Exhibition, April 3-6, Barcelona, Spain.
Huong, H. T., et al., 2017, Application of Geochemical Technique to Reduce Allocation Cost for Commingled Production Wells from Multiple Reservoirs, Petrvietnam Journal, vol. 10, p 45-50.
Jweda, J. et al., 2017, Optimizing Field Development Strategy using Time-lapse Geochemistry in Eagle Ford, Unconventional Resources Technology Conference, July 24-26, 2017, Austin, Tex.
Liu, F., el al., 2017, Time-lapse Geochemistry (TLG) Application in Unconventional Reservoir Development, Unconventional Resources Technology Conference, July 24-26, 2017, Austin, Tex.
Huang, R., J. el al., 2000, Allocation of Commingled Pipeline Oils to Field Production, Organic Geochemistry, v. 31, p 1463-1474.
Kaufman, R. L., et al. 1987, A New Technique for the Analysis of Commingled Oils and Its Application to Production Allocation Calculations, 16th Annual Indonesian Petro. Assoc., IPA 87-23/21, p 247-268.
Kaufman, R. L., et al., 1990, Gas Chromatography as a Development and Production Tool for Fingerprint Oils from Individual Reservoirs: Applications in the Gulf of Mexico, Proceedings of the 9th Annual Research Conference of the Society of Economic Paleotologists, and Mineralogists, New Orleans, p 263-282.
McCaffrey, M. A., et al., 1996, Using Biomarkers to Improve Heavy Oil Reservoir Management: An Example from the Cymric Field, Kern County, Calif., AAPG Bulletin, v. 80, p 904-919.
Peters, K., et al., 2008, De-convoluting Mixed Crude Oil in Prudhoe Bay Field, North Slope, Ak., Organic Geochemistry, v. 39, p 623-645.
McCaffrey, M. A., el al., 2012, Oil Fingerprinting Dramatically Reduces Production Allocation Costs, World Oil, March 2012, p 55-59.
Baskin, D. K., et al, 2014, Allocation the Contribution of Oil from the Eagle Ford Formation, the Buda Formation, and Austin Chalk to Commingled Production from Horizontal Wells in South Texas Using Geochemical Fingerprinting Technology, AAPG Annual Conventional, May 19-23, 2013, Search and Discovery Article #41268.
McCaffrey, M. A., et al., 2011, Geochemical Allocation of Commingled Oil Production or Comingled Gas Production, SPE Western North American Regional Meeting, May 7-11, 2011, Anchorage, Ak., USA.
McCaffrey, M. A., et al, 2016, Applying Oil Fingerprinting to Unconventional Reservoirs in the Permian Basin for Characterization of Frac Height and Quantification of the Contribution of Multiple Formations to Commingled Production, Unconventional Resources Technology Conference (URTec), Aug. 1-3, 2016, San Antonio, Tex., USA.
Geochemical fingerprinting provides a more direct method to monitor a reservoir through information collected directly from the produced oil and/or oil extracted from rock samples, and has some application in monitoring conventional reservoir production, as described above. However, there is a need in the art for such methods and systems using geochemical fingerprinting that provide monitoring of the unconventional reservoir in all three dimensions. In this manner, the unconventional reservoir development plan may be adjusted to improve reservoir economics and reduce environmental impacts.